New station enhances Mount Rainier’s lahar detection network

Release Date:

New station expands scientists' capabilities to detect unrest and provide rapid notification of hazards to emergency officials and the public.

Station PARA at Mount Rainier

Seismic and infrasound station PARA, installed October 6-8, 2020 at Mount Rainier.

(Credit: Elizabeth Westby, USGS-Cascades Volcano Observatory. Public domain.)

During October 6-8, 2020, a USGS-Cascades Volcano Observatory field team installed a new monitoring station near the lower parking lot at Paradise, on Mount Rainier. The seismic and infrasound array are part of the volcano’s monitoring and lahar detection network.

The seismometer detects ground vibrations that can occur as a result of magmatic, hydrothermal, and faulting processes beneath the volcano. The seismometer also detects ground motion associated with above-ground phenomenon, like the noisy, bouncing, rolling, falling mass of debris, rock, or ice.

NAGT intern installs an infrasound array at Mount Rainier

NAGT intern Emily Bryant installs one of three infrasound sensors at volcano monitoring station PARA, at Mount Rainier.

(Credit: Elizabeth Westby, USGS-Cascades Volcano Observatory. Public domain.)

Debris, rock and ice avalanches also generate low frequency sound waves that propagate in the atmosphere. The energy of the wave is between about 0.5 and 20 hertz, which is below the threshold of human hearing. But these atmospheric waves can be detected by infrasound sensors. At least three infrasound sensors make up an array. As sound waves pass each instrument, there is a small time difference in arrivals. Scientists use that difference to calculate a back azimuth, or direction that the sound came from, and the velocity of the wave sweeping across the array path.

 

Geophysicist checks data output at Mount Rainier station

A seismologist with the Cascades Volcano Observatory checks the data output on a newly installed monitoring station at Mount Rainier.

(Credit: Elizabeth Westby, USGS-Cascades Volcano Observatory. Public domain.)

With both seismic and infrasound data, scientists can provide more precise information to land managers, emergency managers and public about the location, timing, duration and relative vigor of an event. This leads to improved early hazard warnings for people and communities near this high-threat volcano. 

Additional lahar monitoring stations are currently under consideration for other areas within Mount Rainier National Park.